This edition of the ‘what is…?‘ feature is a bit of a two-parter, as I don’t see much point in describing diegetic sound without describing non-diegetic sound at the same time.
Diegetic sound, also known as actual sound, is any sound whose source physically exists in the world of the film. This could be in the form of pretty much anything: characters talking, a gunshot, a dog barking, a radio, musical instruments. Diegetic sound may be on-screen or off-screen, but must emanate from action within the film.
Non-diegetic sound, also known as commentary sound, is sound whose source is not a part of the film’s world, in that it doesn’t comes from anything on screen or implied to come from somewhere off screen. Non-diegetic sound is added to film in post-production. Examples of non-diegetic sound include voiceovers and narration, mood music and soundtrack/score, and sound effects added for dramatic effect.
Diegetic and non-diegetic sound are often used together, as shown in this brilliant scene from The Shawshank Redemption.
The clip starts with the shuffling of records, a dripping tap, a prison guard talking – all diegetic sound. Then Andy puts on the Mozart record which plays out of the PA system. This is still diegetic sound, as even when the shot changes and the record player itself isn’t in shot, it still exists within the world of the film.
Then, at around the 2 minute mark, we hear one of Red’s voiceovers, an example of non-diegetic sound whilst the diegetic sound of the record continues in the background.
Now look at what can happen when the non-diegetic sound is taken out of a scene, as shown in this clip made by Paul Olohan from Zombieland…
Switching it up
Filmmakers may segue from diegetic to non-diegetic sound or vice-versa. For example, a character may be listening to the radio, an example of diegetic sound, but the music from the radio may then continue into the following scene and can no longer be heard by the character, thus becoming non-diegetic. This is sometimes known as trans-diegetic.
Filmmakers may also have a bit of fun with sound, leading us to believe it’s either diegetic or non-diegetic, but then revealing it to be the other. See the following clip from Blazing Saddles for instance…
Similarly, in this clip of Stranger Than Fiction, we hear a voiceover narration, which would ordinarily be considered non-diegetic. However, we soon discover that Will Ferrell’s character can actually hear the voiceover, suggesting that it is, in fact, diegetic.
Do you have any favourite uses or sound in film, either diegetic or non-diegetic? If so, let me know in the comments below.
For more entries in the ‘What is…?’ series, click here and (hopefully) learn a little bit about deep focus, chiaroscuro, German Expressionism, and more.